Carburetor for internal combustion



Dec. 24, 1940. R M GRQSJEAN 2,225,989

CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 15, 1939 3 Sheets-Sheet l INVENTOR.

Dee 1940- R. M. GROSJEAN 2,225,939

I CARBURE-TOR FOR INTERNAL COMBUSTION ENGINES Filed Au 15, 1939 s Sheets-Sheet 2 '7/2/2. 7/2/6? 72/4- w5 Fwd IN VENT OR.

Dec. 1940- R. M. GROSJEAN 2,225,939

CARBURETOR FOR INTERNAL COMBUSTION ENGINES Filed Aug. 15, 1939 3 Sheet-Sheet 3 Patented Dec. 24, 1940 UNITED STATES PATENT OFFICE Reuben M. Grosjean, Omaha, Nebr. Application August 15, 1939, Serial No. 290,184

4 Claims.

My invention relates to improvements in carburetors or charge forming devices which have a throttle and which meter air and hydro-carbon fuel to internal combustion engines through a wide range of speeds and loads; and the objects of my improvement are, first, to provide high air velocity in the mixing chamber at all engine speeds and loads; second, to provide a practical means by which the increase and decrease in volume of air passing through the carburetor, automatically varies the area of the air metering tube throughout the range of speeds and loads; third, to provide a fuel metering valve to operate in conjunction with the varying air metering tube, which will accurately meter fuel throughout the range of said varying air metering tube, which will not be easily clogged with sediment, and will not wear rapidly; fourth, to sum up objects, to provide in a carburetor, a dependable combination of mechanism which will give good atomization at all speeds and loads, and will accurately meter hydro-carbon fuel to internal combustion engines throughout the wide range of speeds and loads as required in modern automobile engines.

Other and important objects of this invention will be apparent from the disclosures in this specification and accompanying drawings.

The invention (in two preferred forms) is illustrated on the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a center section of a carburetor embodying the features of the invention.

Figure 2 is a section on the line AA Fig. 1, but with movable members in a different position.

Figs. 3, 4, 5, 6 and 'I are sections on line BB Fig. 1, and each represents a different position 40 of a movable member.

Figs. 8 and 9 are sections similar to Figs. 3 and 7 respectively, but showing a modified construction.

Fig. 10 is a center section of a further modified form of carburetor embodying the features of the invention.

Fig. 11 is a section on line C-C Fig. 10, but with movable members in a different position.

Figs. 12, 13, 14, 15 and 16 are sections on the line D--D Fig. 10, and each represent a different position of a movable member.

Figs. 17, 18, 19, 20 and 21 are enlarged sections on the line E-E Figs. 1 and 10, and each represent a different position of a movable member.

Figs. 22 and 23 each show a part of Figs. 1 and 10 drawn to an enlarged scale.

Similar numerals refer to similar parts throughout the several views.

The carburetor housing 24 is formed with a downwardly discharging mixing chamber in the form of an air metering tube 25. The housing has an air intake at 26 and a mixture outlet through the throttle body 21 which is bolted to the lower face of said housing and has a mounting flange for attachment to the manifold of the engine. The throttle fly is shown at 28 and the throttle shaft at 29. In the upper part of the housing the control cylinder 30 is formed. Said control cylinder is closed at its upper end by the cover 3| and the cap 32. The piston 33 is adapted to slide in said control cylinder and has limbs 34 projecting downward from an end and adapted to slide between the vertical partitions 35. Two, three or more of these partitions may be used. In Figs. 1 to 7 inclusive two partitions are used and in Figs. 8 to 16 inclusive three are used. The inner surfaces 36 of said partitions are tapered from a point just above the fuel orifice 31 to their lower ends so that they diverge and leave a larger opening at the lower end. Likewise, the inner surfaces of said limbs are tapered so that they diverge and leave a larger opening at the lower end. Slots with parallel sides are formed between said limbs, and it is the sides of these slots which slide against said partitions so that said limbs are guided by said partitions. When only two partitions are used, said limbs should be guided at their circumference in addition to being guided at the slots. Said parti- 3 tions and the inner surfaces of said limbs jointly form the walls of the air metering tube. Above the partitions the slots are open and allow air to enter the air metering tube. The combined area of the openings through these slots is at all times much greater than the area of the air metering tube at the fuel orifice. The upper end of the piston is guided by the wall of the control cylinder. Circular grooves as shown in Fig. 23 may be formed in the wall of the control cylinder to lessen the leakage of air past the skirt of the piston or packing of some kind may be used on the piston to seal it and to damper out the piston slap. The piston with said limbs is caused to rise higher in the control cylinder when the pressure of the air above the piston is lowered, and is returned to its lowest position by the spring 38 with the aid of gravity when the air pressure on both sides of said piston is equal. The air passage 39 connects the upper end of the control cylinder with the lower end of the air metering tube and serves to equalize the pressure at these two points and thus to control the movements of the piston. The check valve 40 prevents backfire pressure from reaching the control cylinder and operates only when air flows back to said cylinder at high velocity.

The fuel metering valve is composed of the fuel metering pin 4! and the fuel metering valve body 42. The fuel metering pin has a ball formed on its upper end and is connected to the piston 33 by a double ball joint composed of the pitman A3 and the adjusting screw 44. The spring 45 holds the slack out of the threads and prevents the adjusting screw from being rotated by vibration. The pin 46 prevents the fuel metering pin "from being rotated. The fuel metering valve body 42 is bored to fit the fuel metering pin and has an annular groove 41 with an opening which connects with the fuel passage 48 which passage terminates in the fuel orifice 31. The part of the ,fuel metering valve body above said annular groove forms a guide forthe fuel metering pin, and the part below said groove serves with the fuel metering pin to meter the fuel. The lower end of the fuel metering pin has a groove which I prefer to make spiral. This groove is graduated in depth and in width being deepest and widest at the lower end and serves to meter the fuel which passes through the valve. The fuel metering valve body is'held-in place by the clamp E9 and a screw at 50. 'This form of fuel metering valve is, to a great degree, self cleaning. As the fuel metering pin is pulled through the valve body,

particles of dirt or lint which might accumulate and clog other types of valves, are pulled through by the spiral groove and pass out at the fuel orifice. There are no narrow passages as around a tapered metering pin and no multiplicity of small jets or valves.

The float 5| which operates a valve (not shown on the drawings) holds the fuel at an approximately constant level in the fuel reservoir 52. A choke mechanism which serves to enrich the mixture has been omitted from the drawings.

The operation of the various units co-acting to form a complete carburetor has been described in connection with the description of the structure, so that only a brief rsum of the operation is believed to be required.

In operation, the carburetor is bolted to the intake manifold of the engine. Thespeed of the engine is regulated by opening orclosing the throttle fly 28. A throttle stop (not shown on the drawings) is so adjusted that the throttle can only be closed to a point which will give the desired idling speed. When the engine is not running the piston 33'with limbs 34 rests in its lowest position and may remain in this position through low idling speed. This position gives the smallest opening through the .air metering tube. When the throttle is opened-more air is drawn through the carburetor and the air pressure is lowered in the air metering tube. This drop in pressure is carried through the air passage'39 to the space above the piston and the piston is caused to rise to a point where the pressure of the spring 33 balances the effective air pressure on the piston. This movement of' the piston increases the size of the opening through the air meteringtube. As the engine speed increases the piston riseshigher and further increases the size of the opening through the air metering tube. The height towhichthe'piston is raised is determined, not primarily by the amount the throttle is open, but by the volume of air passing through the carburetor. By this arrangement a comparatively high air velocity is obtained at the fuel orifice at low engine speed without having excessive air velocity andexcessive restriction of air flow at high engine speeds.

The fuel metering pin is attached to the aforesaid piston and is raised or lowered with each respective movement of the piston. The groove in the fuel metering pin is so graduated in depth and in width as to give the correct amount of fuel for each size of opening through the air metering tube. Fig. 17 is a cross section of the fuel metering valve and shows this groove at idling speed, and Figs. 18, 19, 20 and 21 each show the groove at a higher speed. The fuel metering valve should be adjusted to give the correct mixture at low speed. To make this adjustment cap 32 is removed and either an ordinary screw driver or a special tool may be used to turn the adjusting screw 44. If an ordinary screw driver is used the opening at the top should be closed with a piece of sheet rubber while the adjustment is being made so that said adjustment can be made with the engine running.

The path followed by air in passing through the carburetor is as follows: Air enters the housing 2 through the air intake 25 and is distributed around all sides of the air metering tube. From here air flows through the slots formed between the limbs of the piston to the central cone shaped opening formed between said limbs. The air then flows downward, entering the air metering tube at a point just above theifuel orifice 3i.

Fuel from said orifice mixes with the air as it continues downward through the air metering tube. The mixture then passes the throttle fly f8 and enters the intake manifold of the engine.

The use of partitions in the housing, and limbs on a control. piston to close the openings between said partitions and to form the varying walls of the air metering tube, has important advantages over other types of means which have been devised to vary the cross-section area of the air metering tube of carburetors. These advantages as I see them arez-The fuel orifice may be so placed as to be at-the center of the air stream throughout'the range of the air metering tube. Thus, there is little chance for liquid fuel to be carried into the manifold by adhesion to the Walls of the air metering tube. The fuel orifice may be so placed as to be at the point of highest air velocity throughout the range of the'air metering tube. This will give better-atomization and better control of the flow of the fuel from the fuel reservoir to the'fuel orifice. This form of air metering tubeuses no shafts, pivots or levers and allows the use of a simple and efficient arrangement of the means interconnecting the movable member of the air metering tube and the movable member of the fuel metering valve. This form of air metering tube allows the use of a short fuelpassage from the fuel reservoir to the fuel orifice.

With the carburetorshown in Figs. 1 to 9 inclusive, all of the air passes through the slots formed between the limbs of the piston and through the central air metering tube.

The carburetor shownin Figs. 10 to 16 inclusive is constructed differently in the air'metering tube. The limbs of the piston are tapered both inside-and outside and are guided only by the three-partitions. When thepiston is raised the size of thecentral opening through the air metering tube is increased, and the width of the openings outside said limbs is increased. Part of the air flows through the central opening and part outside said limbs.

The latter construction has the advantages of permitting better design throughout the air metering tube and the air passages leading to same. The taper of the walls of the air metering tube is less with this construction which gives the area of the openings through the slots a larger margin over the area of the opening through the air metering tube. As shown in Figs. 10 to 16, a ratio of about four to one is obtained. There is also the advantage of the double venturi in which the fuel is first mixed with the central stream of air, and then with the outer stream which surrounds it.

I am aware that numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted, otherwise than necessitated by the prior art.

I claim as my invention:

1. In a carburetor, the combination of a housing having an opening formed therein, said opening having longitudinal ribs or partitions the inner walls of which are curved to conform to the longitudinal section of a Venturi tube, a pressure responsive member comprising a piston having limbs disposed to fill out the spaces between said partitions and together with the walls of said partitions their inner walls comprising the mix ing chamber in the form of said Venturi tube the cross section of which may in effect be varied by shifting said limbs longitudinally relative to said housing and its partitions, a fuel orifice in said Venturi tube, a fuel metering valve actuated by said pressure responsive member and adapted to control the flow of fuel from said fuel orifice, and an air passage connecting said Venturi tube with said pressure responsive member.

2. In a carburetor, the combination of a housing having an opening formed therein, said opening having longitudinal ribs or partitions the inner walls of which are curved to conform to the longitudinal section of a Venturi tube, a member responsive to changes in the air pressure in said Venturi tube comprising a piston having limbs disposed to fill out the spaces between said partitions and together with the walls of said partitions their inner walls comprising the mixing chamber in the form of said Venturi tube the cross section of which may in effect be varied by shifting said limbs longitudinally relative to said housing and its partitions, a fuel orifice in said Venturi tube, and a fuel metering valve actuated by said piston and disposed to control the flow of fuel from said fuel orifice.

3. In a carburetor, the combination of a housing having an opening formed therein, said opening having longitudinal ribs or partitions the inner walls of which are shaped to conform to the longitudinal section of a Venturi tube, a member responsive to changes in the air pressure in said Venturi tube comprising a piston having limbs disposed to fill out the spaces between said partitions and together the walls of said partitions and of said limbs forming the mixing chamber in the form of said Venturi tube the effective cross section of which is Varied by the shifting of said limbs longitudinally relative to said housing and its partitions, a fuel orifice in said Venturi tube, and a fuel metering valve actuated by said piston and disposed to control the flow of fuel from said fuel orifice.

4. In a carburetor, the combination of a housing having an opening formed therein, said opening having longitudinal ribs or partitions the inner walls of which are shaped to conform to the longitudinal section of a Venturi tube, a member responsive to changes in the air pressure in said Venturi tube comprising a piston having limbs disposed to fill out the spaces between said partitions and together the walls of said partitions and of said limbs forming the mixing chamber in the form of said Venturi tube the effective cross section of which is varied by the shifting of said limbs longitudinally relative to said housing and its partitions, a fuel orifice at the approximate center of the air stream and approximately at the point of highest air velocity in said Venturi tube, and a fuel metering valve actuated by said piston and disposed to control the flow of fuel from said fuel orifice, substantially as described.

REUBEN M. GROSJEAN. 

